A self-healing composite passivator and a passivation treatment method for inhibiting the oxidation of pyrite

Abstract

The present invention discloses a self-healing composite passivator and a passivation treatment method for inhibiting the oxidation of pyrite. The passivator includes a nano filler, lauroxone, and a silane coupling agent. Among them, the nano filler is composed of a nano passivator coated with a polyelectrolyte layer, and the nano passivator is composed of a guest passivator loaded in halloysite nanotubes. Pyrite is placed in the self-healing composite passivator for stirring reaction. The passivator can form a passivation film with self-repair function on the surface of pyrite at room temperature, protecting pyrite from the corrosion of external acidic media, and having the advantages of simplicity, high efficiency, mildness, safety, environmental protection and economy.

Description

Technical Field

[0001] The present invention relates to a passivator and a passivation treatment method for inhibiting the oxidation of pyrite, in particular to a self-healing composite passivator and a passivation treatment method for inhibiting the oxidation of pyrite, belonging to the technical field of environmental metal pollution treatment. Background Art

[0002] With the utilization of mineral resources, a large amount of tailings and waste rocks containing sulfide minerals are generated in mines, and pyrite is the most typical and abundant sulfide mineral among them. When exposed to air and water, pyrite will undergo a series of chemical reactions and finally be oxidized to form acid mine drainage (AMD). If AMD is discharged without proper treatment, it will cause serious damage to the surrounding groundwater, natural water bodies and soil, thus affecting the health of surrounding animals and plants. Therefore, AMD has become one of the most serious environmental problems faced by the mining industry. The surface passivation method refers to forming a passivation film on the surface of the mineral by means of a chemical reaction between the passivator and the metal mineral to coat the surface of the mineral, so as to achieve the purpose of isolating oxidation substances such as air and water. This method has the advantages of low cost and good treatment effect.

[0003] In recent years, organosilanes have been widely used in the research of tailings passivation and metal anti-corrosion due to their advantages of non-toxic, pollution-free and oxidation resistance. However, there are two deficiencies in the process of coating silane on pyrite by organosilanes. The first problem is that organosilane passivators need to passivate pyrite at 50-100 °C, which is very difficult to achieve in actual applications, and this limits the practical application of organosilanes in real tailings piles. The second is that after the silane is eroded by acidic media for a long time, a large number of cracks are generated on the surface of the passivation layer.

[0004] At present, some studies have adopted adding halloysite nanotubes to silane. The hollow lumen of halloysite nanotubes can load another small molecule guest passivator in it, and then copper ions are used as end plugs to combine with the small molecule guest passivator, so that the passivator is encapsulated in halloysite. When the original passivation film is damaged, the small molecule passivator is released again to repair the damaged part, achieving the effect of intelligent self-repair. However, since copper ions can only combine with specific small molecule guest passivators, this encapsulation method of guest passivators limits the application of guest passivators with better effects. Therefore, there is an urgent need to find a new type of passivator that is environmentally friendly, convenient and fast, which has the characteristics of low cost, simple operation, room temperature passivation, and universality in the encapsulation of guest passivators, and overcomes the deficiencies of organosilane passivators and self-repair methods in the prior art. Summary of the Invention

[0005] Aiming at the disadvantages and deficiencies existing in the prior art, the first object of the present invention is to provide a self-healing composite passivator. In this passivator, lauroxone and silane coupling agent play the role of main passivators. An organic protective layer is formed at the corrosion active sites through the formation of insoluble complexes between lauroxone and metal ions, and lauroxone can crosslink with the silane coupling agent to form a composite passivation film to enhance the passivation effect. At the same time, when the main passivator in the passivator is damaged and corrosion is about to occur, the polymer electrolyte layer on the surface of the nano-filler in the passivator swells, thereby stimulating the release of the encapsulated guest passivator to continue to prevent the corrosion of pyrite, and the effects of passivation and self-healing at room temperature can be achieved. Meanwhile, the encapsulation of the tubular halloysite loaded with the guest passivator by the polyelectrolyte layer is independent of the type of the guest passivator, which broadens the selection range of the guest passivator.

[0006] The second object of the present invention is to provide a passivation treatment method for inhibiting the oxidation of pyrite. This method has the advantages of high passivation efficiency, simple operation, environmental friendliness, etc.

[0007] To achieve the above object, the present invention provides a self-healing composite passivator, which passivator comprises a nano-filler, lauroxone and a silane coupling agent; the nano-filler is composed of a nano-passivator coated with a polyelectrolyte layer; the nano-passivator is composed of a guest passivator loaded in halloysite nanotubes.

[0008] The self-healing composite passivator of the present invention has a multi-layer passivation effect. The synergistic effect of lauroxone and the organosilane coupling agent is utilized to play a primary passivation role, and the guest passivator encapsulated by the nano-filler plays a secondary passivation role. The primary passivation effect can effectively inhibit the oxidation of pyrite at room temperature. And when the main passivator is damaged and corrosion is about to occur, the secondary passivation effect is immediately exerted, the polyelectrolyte layer on the surface of the nano-filler swells, thereby stimulating the release of the guest passivator to continue to prevent the corrosion of pyrite, achieving the self-healing effect and effectively prolonging the passivation time of pyrite.

[0009] The present invention utilizes that during the corrosion process, a pair of electrons on the hydroxyl group of lauroxone delocalize and undergo a chemical rearrangement, thereby forming a 1:1 or 2:1 complex with metal ions. These insoluble complexes generated by lauroxone will be adsorbed to the corroded area on the metal surface, blocking the corrosion active sites. The formed organic protective layer can seal and isolate the damaged metal substrate from the corrosive medium. Thereby, an inhibitory effect on the corrosion process of the metal is produced. At the same time, the quinone structure of lauroxone can crosslink with the long-chain hydrolyzed silane coupling agent having a mercapto group to form a composite passivation film. This composite passivation film is denser and more hydrophobic than the organic protective layer, greatly improving the stability of the passivation film.

[0010] As a preferred solution, the mass ratio of nanofiller, lorsoxone and silane coupling agent in the self-healing composite passivator is 0.1-2:0.01-0.2:3-5. The key in the present invention is to regulate the mass ratio of nanofiller, lorsoxone and silane coupling agent in the self-healing composite passivator so that it produces a synergistic effect within a suitable range. The present invention is conducive to improving the self-repairing performance by controlling the addition amount of nanofiller within a suitable range. When the amount of nanofiller added is too little, when corrosion occurs, the released guest passivator is too little, and an effective passivation film cannot be formed; and when the amount of nanofiller added is too much, due to the strong mutual electrostatic repulsion between molecules, the area occupied by the nanofiller on the surface of pyrite is reduced, and the passivation efficiency is reduced. The passivation effect of lorsoxone on pyrite is proportional to the change in the amount of lorsoxone used. The higher the amount of lorsoxone used, the better the passivation effect on pyrite, but when the amount is too high, it will be difficult to dissolve and form agglomeration. When the dosage of lorsoxone is too low, it is difficult to generate an effective coated passivation film on the surface of pyrite. At the same time, the dosage of silane coupling agent will also affect the effect of the passivation film. When the dosage of silane coupling agent is too low, the passivation film produced on the surface of pyrite is not dense enough, and the micropores or microcracks in the passivation film easily cause pyrite to be corroded by the oxidizing medium again, thereby reducing the stability of the passivation film; and if the dosage of silane coupling agent is too high, the use cost of the passivation agent will be greatly increased, and the passivation efficiency will not be significantly improved beyond the selected range of the present invention. In addition, the mass ratio of lorsoxone and silane coupling agent in the present invention must be in the range of 0.01-0.2:3-5, and controlling the mass ratio of lorsoxone and silane coupling agent in a suitable range is conducive to improving the passivation effect. If the mass ratio is too low, the hydrolysis condensation reaction between silane molecules plays a dominant role, and it is difficult to further cross-link with the Lawson passivation film on the surface of pyrite to form a double-layer passivation film; when the mass ratio of lawson ketone and silane coupling agent is too high, the double-layer passivation film formed by the silane coupling agent on the surface of pyrite is not dense enough and has poor stability.

[0011] As a preferred solution, the loading amount of the guest passivator in the nano passivator is 0.1-5wt%, more preferably 0.5-1.5wt%. The guest passivator of the present invention is a small molecule guest passivator such as 8-hydroxyquinoline, triethylenetetramine, benzotriazole, etc., more preferably 8-hydroxyquinoline.

[0012] As a preferred solution, the silane coupling agent is one of γ-mercaptopropyltrimethoxysilane, tetraethoxysilane, n-propyltrimethoxysilane and methyltrimethoxysilane.

[0013] As a preferred embodiment, the polyelectrolyte layer includes a cationic polyelectrolyte layer and an anionic polyelectrolyte layer; the cationic polyelectrolyte layer is composed of poly(diallyldimethylammonium chloride) (PDDA); the anionic polyelectrolyte layer is composed of sodium polystyrene sulfonate (PSS).

[0014] As a preferred embodiment, the polyelectrolyte layer is alternately composed of a cationic polyelectrolyte layer and an anionic electrolyte layer. The present invention also utilizes the fact that halloysite nanotubes have a typical multi-walled tubular structure of aluminosilicate, and their outer surface is negatively charged. Therefore, a layer-by-layer self-assembly method can be used to coat multiple layers of polyelectrolyte layers with positive and negative charges on the nanotube surface. The polyelectrolyte layer exhibits small intermolecular repulsion under neutral conditions, resulting in the contraction of the polyelectrolyte layer, so that the guest passivator is encapsulated inside the halloysite nanotubes. Under acidic conditions, due to the high charge density, electrostatic repulsion is generated in the polyelectrolyte layer, the polyelectrolyte layer expands, and the guest passivator is released, forming a new passivation film in the corrosion area on the surface of pyrite, extending the protection time of the passivator for pyrite. And because the method of encapsulating the guest passivator utilizes the negative charge on the outer surface of halloysite, it is independent of the type of guest passivator wrapped inside, greatly expanding the range of selectable guest passivators.

[0015] As a preferred embodiment, the polyelectrolyte layer is alternately composed of 1 to 3 layers of cationic polyelectrolyte layers and 1 to 3 layers of anionic polyelectrolyte layers. When the present invention only uses 1 layer of cationic polyelectrolyte layer for coating, the situation of incomplete coating will occur. Coating the anionic polyelectrolyte layer on the cationic polyelectrolyte layer can not only enhance the coating effect, but also use the electrostatic attraction between the cationic polyelectrolyte layer and the anionic polyelectrolyte layer to wrap the entire halloysite into a whole, so as to realize the encapsulation of the guest passivator. The present invention helps to control the release efficiency of the guest passivator by controlling the number of layers of the polyelectrolyte layer within a suitable range. If the number of coated layers is too small, the coating effect of the polyelectrolyte layer on the guest passivator is not good under neutral conditions, and the guest passivator will be released in advance without acidic corrosion; when the number of polyelectrolyte coatings is too large, when corrosion occurs, the polyelectrolyte layer cannot swell in time to release the guest passivator therein.

[0016] As a preferred embodiment, the self-healing composite passivator contains a solvent; the solvent contains water and an alcohol solvent; the total mass content of the nano filler, lauroxone and silane coupling agent in the self-healing composite passivator is 1 to 10%.

[0017] As a preferred embodiment, the preparation method of the nano filler is to mix a solution containing a guest passivator and halloysite nanotubes, and then alternately add a cationic polyelectrolyte solution and an anionic polyelectrolyte solution for coating, and then it is obtained.

[0018] As a preferred embodiment, the concentration of the cationic polyelectrolyte solution is 1 to 2 wt%.

[0019] As a preferred embodiment, the concentration of the anionic polyelectrolyte solution is 2 to 4 g / L.

[0020] As a preferred embodiment, the preparation method of the self-healing composite passivator is to mix a solution containing lauroxone and a silane coupling agent, adjust the pH of the solution to weakly alkaline, and then add a nano filler and mix to obtain it. By adjusting the pH of the mixed solution to weakly alkaline in the present invention, it is beneficial for the silane coupling agent to crosslink with lauroxone, realizing the secondary passivation of the pyrite surface, thereby constructing a denser hydrophobic crosslinked passivation film on the pyrite surface under mild conditions.

[0021] The present invention also provides a passivation treatment method for inhibiting the oxidation of pyrite, which is to place the pyrite in the above-mentioned self-healing composite passivator and carry out a stirring reaction.

[0022] As a preferred embodiment, the stirring reaction conditions are: temperature is 25 to 35 °C, time is 4 to 6 h, and pH is 1 to 7. Under the condition of room temperature in the present invention, lauroxone, the silane coupling agent reagent, and the nano filler can cooperate to construct a dense hydrophobic crosslinked passivation film with self-healing performance on the pyrite surface, while directly using a silane passivator requires a high-temperature reaction to form a silane passivator.

[0023] As a preferred embodiment, the mass-volume ratio of the pyrite to the self-healing composite passivator is 1 g: 10 to 20 mL.

[0024] As a preferred embodiment, the particle size of the pyrite is 75 to 150 μm. The smaller the particle size of the pyrite, the larger its specific surface area, and the more sufficient the contact between the passivator and the pyrite surface, making the passivation effect of the passivator on the pyrite better.

[0025] As a preferred embodiment, after the pyrite completes the stirring reaction in the passivator, solid-liquid separation is carried out, and the solid obtained by solid-liquid separation is air-dried at a temperature of 15 to 30 °C for 24 to 48 h.

[0026] Compared with the prior art, the beneficial technical effects brought by the technical solution of the present invention:

[0027] 1) The present invention introduces lauroxone into the organosilane passivation film to synergistically passivate pyrite, constructing a denser hydrophobic crosslinked passivation film on the pyrite surface, providing a better oxidation barrier effect for pyrite.

[0028] 2) A complex cross-linked passivation film of lausonine-silane coupling agent was constructed on the surface of pyrite under mild conditions through a simple and efficient method, which can effectively protect pyrite from the erosion of external oxidants, thus suppressing or slowing down the generation of acid mine drainage at the source, greatly reducing the treatment cost of acid mine drainage, and breaking through the bottleneck problems encountered in the use of current organosilane passivators and lausonine passivators.

[0029] 3) Nano-fillers were introduced into the lausonine-silane coupling agent, making the passivator have a self-healing function, which can effectively repair local damage of the passivation film, with high passivation efficiency, improve the stability of the passivation film, and extend the effective protection time. The use frequency of the passivator can be reduced, further controlling the cost.

[0030] 4) The encapsulation of halloysite by the polyelectrolyte layer used in the present invention is independent of the guest passivator in the halloysite nanotubes, making the encapsulation universal, broadening the selection range of guest passivators, enabling better guest passivators to be applied to halloysite, and the prepared nano-inhibitor achieves the purpose of acid-responsive release of the guest passivator.

[0031] 5) The preparation of the passivator of the present invention and the film coating process on the surface of pyrite are simple and environmentally friendly, and have good application prospects in the treatment of tailing pollution. Description of the Drawings

[0032] Figure 1 It is a graph showing the change of total iron leaching concentration of pyrite in hydrochloric acid for Examples 1-4 and Comparative Examples 1-3.

[0033] Figure 2 It is a graph showing the change of SO 4 2- leaching concentration of pyrite in hydrochloric acid for Examples 1-4 and Comparative Examples 1-3.

[0034] Figure 3 It is a graph showing the change of 8-hydroxyquinoline release concentration of nano-fillers wrapped with four layers of electrolyte layers in Example 5 under the conditions of pure water (pH 6.5), hydrochloric acid solutions with pH values of 1.0, 3.0, and 5.0.

[0035] Figure 4 It is a graph showing the change of 8-hydroxyquinoline release concentration of nano-fillers for Examples 5-7 and Comparative Example 4 under the condition of different numbers of polyelectrolyte layers in hydrochloric acid with pH = 1.

[0036] Figure 5 It is a graph showing the change of 8-hydroxyquinoline release concentration of nano-fillers for Example 5, Example 8, Example 9 and Comparative Example 5 under the condition of different numbers of polyelectrolyte layers in pure water. Detailed Description of the Invention

[0037] In order to facilitate the understanding of the present invention, the present invention will be described in more comprehensive and detailed manner in conjunction with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.

[0038] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0039] Unless otherwise specified, all reagents and raw materials used in the present invention are commercially available products or products that can be prepared by known methods.

[0040] Example 1

[0041] (1) First, 0.5 g of 8-hydroxyquinoline was dissolved in 100 mL of acetone, and then 5 g of halloysite powder was added. After ultrasonic treatment for 10 min, the mixture was transferred to a vacuum dish. After the vacuum dish was closed, the vacuum pump was turned on to make the vacuum degree in the sealed system reach 0.09 MPa and maintained for 40 min. This was a loading cycle. After the loading was repeated three times, the mixture was washed with deionized water and centrifuged. The centrifuged product was dried and ground into powder.

[0042] (2) Add polydiallyldimethylammonium chloride to the aqueous solution to prepare 200mL of 2wt% polydiallyldimethylammonium chloride solution; then add 5.85g of sodium chloride to 200mL of the aqueous solution, and then add 0.8g of sodium polystyrene sulfonate powder thereto to obtain a 4g / L sodium polystyrene sulfonate solution. First, add the HNT-HQ powder obtained in step (1) to the polydiallyldimethylammonium chloride solution, stir for 25min at a vacuum degree of 0.09Mpa and 25°C, then let the suspension stand for 5 minutes, wash twice with water, centrifuge and discard the supernatant, then redisperse the precipitate in 200mL of 4g / L sodium polystyrene sulfonate solution, stir for 25min at a vacuum degree of 0.09Mpa and 25°C, let stand for 5min, wash twice with water, centrifuge and discard the supernatant.

[0043] (3) Repeat step (2) to obtain a nanofiller coated with four layers of polyelectrolyte after drying and grinding.

[0044] (4) 0.1 g of lorsulphonate was dissolved in 50 mL of ethanol solution and stirred thoroughly to prepare a lorsulphonate solution with a concentration of 2 g / L; a mixed solvent with a volume ratio of ethanol to water of 8:1 was prepared, and γ-mercaptopropyltrimethoxysilane (PropS-SH) was added thereto to prepare 50 mL of a 5% (v / v) organosilane solution.

[0045] (5) Adjust the pH value of the above-mentioned lasoctone solution to 8 with 0.5 mol of ammonia water. Mix the above-prepared organosilane solution with the lasoctone solution, add 1 g of the above-prepared nano filler, and then add 5 g of pyrite powder (particle size is about 100 μm). Stir the mixture at a water temperature of 25 °C for 6 h, then filter out the passivated pyrite powder, dry it at 25 °C for 24 h, and finally obtain passivated-coated pyrite, named PL+HH@PE-1.0 passivated ore.

[0046] (6) Add 1 g of the above passivated ore to 120 mL of hydrochloric acid solution (pH = 1) and react for 60 d. Test the total iron and SO 4 2- concentration in the leaching solution, and it is obtained that compared with the original pyrite ore, the release reduction of the total iron and SO 4 2- concentration are 77.89% and 67.31% respectively.

[0047] Example 2

[0048] (1) First, dissolve 0.5 g of 8-hydroxyquinoline in 100 mL of acetone, then add 5 g of halloysite powder. After ultrasonic treatment for 10 min, transfer it to a vacuum dish. Close the vacuum dish and then turn on the vacuum pump to make the vacuum degree in the sealed system reach 0.09 Mpa and keep it for 40 min. This is one loading cycle. After repeating the loading three times, wash it with deionized water and then centrifuge. Dry the centrifuged product and grind it into powder after drying.

[0049] (2) Add polydiallyldimethylammonium chloride to an aqueous solution to prepare a 200 mL 2 wt% polydiallyldimethylammonium chloride solution; then add 5.85 g of sodium chloride to 200 mL of aqueous solution, and then add 0.8 g of sodium polystyrene sulfonate powder to obtain a 4 g / L sodium polystyrene sulfonate solution. First, add the HNT-HQ powder obtained in step (1) to the polydiallyldimethylammonium chloride solution, stir at a vacuum degree of 0.09 Mpa and 25 °C for 25 min, then let the suspension stand for 5 minutes, wash it twice with water, centrifuge, pour out the supernatant, and then redisperse the precipitate in 200 mL of 4 g / L sodium polystyrene sulfonate solution, stir at a vacuum degree of 0.09 Mpa and 25 °C for 25 min, stand for 5 min, wash it twice with water, and centrifuge and pour out the supernatant.

[0050] (3) Repeat step (2), dry and grind to obtain a nano filler wrapped with four layers of polyelectrolytes.

[0051] (4) Dissolve 0.1 g of lausonone in 50 mL of ethanol solution and stir well to prepare a lausonone solution with a concentration of 2 g / L; prepare a mixed solvent of ethanol:water = 8:1, add γ-mercaptopropyltrimethoxysilane (PropS-SH) to it, and prepare 50 mL of 5% (v / v) organosilane solution.

[0052] (5) Adjust the pH value of the above lausonone solution to 8 with 0.5 mol of ammonia water, mix the above-prepared organosilane solution with the lausonone solution, add 0.5 g of the above-prepared nano filler, and then add 5 g of pyrite powder (particle size about 100 μm), stir the mixture at a water temperature of 25 °C for 6 h, then filter out the passivated pyrite powder, dry it at 25 °C for 24 h, and finally obtain passivated-coated pyrite, named PL+HH@PE-0.5 passivated ore.

[0053] (6) Add the above passivated ore to 120 mL of hydrochloric acid solution (pH = 1) and react for 60 d, and test the total iron and SO 4 2- concentration in the leaching solution, and it is obtained that compared with the original pyrite ore, the release reduction of the total iron and SO 4 2- concentration of the passivated pyrite is 58.48% and 60.71% respectively.

[0054] Example 3

[0055] (1) First, dissolve 0.5 g of 8-hydroxyquinoline in 100 mL of acetone, then add 5 g of halloysite powder, transfer it to a vacuum dish after ultrasonic treatment for 10 min. After closing the vacuum dish, turn on the vacuum pump to make the vacuum degree in the sealed system reach 0.09 Mpa and keep it for 40 min. This is one loading cycle. After repeating the loading three times, wash it with deionized water and then centrifuge, dry the centrifuged product, and grind it into powder after drying.

[0056] (2) Add polydiallyldimethylammonium chloride to an aqueous solution to prepare a 200 mL 2 wt% polydiallyldimethylammonium chloride solution; then add 5.85 g of sodium chloride to 200 mL of aqueous solution, and then add 0.8 g of sodium polystyrene sulfonate powder to obtain a 4 g / L sodium polystyrene sulfonate solution. First, add the HNT-HQ powder obtained in step (1) to the polydiallyldimethylammonium chloride solution, stir at a vacuum degree of 0.09 Mpa and 15 - 30 °C for 25 min, then let the suspension stand for 5 minutes, wash it twice with water, centrifuge and pour out the supernatant, and then redisperse the precipitate in 200 mL of 4 g / L sodium polystyrene sulfonate solution, stir at a vacuum degree of 0.09 Mpa and 25 °C for 25 min, stand for 5 min, wash it twice with water, centrifuge and pour out the supernatant.

[0057] (3) Repeat step (2), and after drying and grinding, a nano filler wrapped with four layers of polyelectrolytes is obtained.

[0058] (4) Dissolve 0.1 g of loxoprofen in 50 mL of ethanol solution and stir well to prepare a loxoprofen solution with a concentration of 2 g / L; prepare a mixed solvent of ethanol:water = 8:1, add γ-mercaptopropyltrimethoxysilane (PropS-SH) to it, and prepare a 50 mL 5% (v / v) organosilane solution.

[0059] (5) Adjust the pH value of the above loxoprofen solution to 8 with 0.5 mol of ammonia water, mix the above-prepared organosilane solution with the loxoprofen solution, add 1.5 g of the above-prepared nano filler, and then add 5 g of pyrite powder (particle size about 100 μm). Stir the mixture at a water temperature of 25 °C for 6 h, then filter out the passivated pyrite powder, dry it at 25 °C for 24 h, and finally obtain passivated-coated pyrite, named PL+HH@PE-1.5 passivated ore.

[0060] (6) Add the above passivated ore to 120 mL of hydrochloric acid solution (pH = 1) and react for 60 d, and test the total iron and SO 4 2- concentration in the leaching solution, and it is obtained that compared with the original pyrite ore, the release reduction of the total iron and SO 4 2- concentrations of the passivated pyrite are 63.79% and 55.35% respectively.

[0061] Example 4

[0062] (1) First, dissolve 0.5 g of 8-hydroxyquinoline in 100 mL of acetone, then add 5 g of halloysite powder, transfer it to a vacuum dish after ultrasonic treatment for 10 min. After closing the vacuum dish, turn on the vacuum pump to make the vacuum degree in the sealed system reach 0.09 Mpa, and keep it for 40 min. This is one loading cycle. After repeating the loading three times, wash it with deionized water and then centrifuge, and dry the centrifuged product and grind it into powder.

[0063] (2) Add polydiallyldimethylammonium chloride to an aqueous solution to prepare a 200 mL 2 wt% polydiallyldimethylammonium chloride solution; then add 5.85 g of sodium chloride to 200 mL of aqueous solution, and then add 0.8 g of sodium polystyrene sulfonate powder to obtain a 4 g / L sodium polystyrene sulfonate solution. First, add the HNT-HQ powder obtained in step (1) to the polydiallyldimethylammonium chloride solution, stir at a vacuum of 0.09 Mpa and 25 °C for 25 min, then let the suspension stand for 5 minutes, wash twice with water, and after centrifugation, pour off the supernatant and redisperse the precipitate in 200 mL of 4 g / L sodium polystyrene sulfonate solution, stir at a vacuum of 0.09 Mpa and 25 °C for 25 min, stand for 5 min, wash twice with water, and after centrifugation, pour off the supernatant.

[0064] (3) Repeat step (2), and after drying and grinding, a nano-filler wrapped with four layers of polyelectrolytes is obtained.

[0065] (4) Dissolve 0.1 g of loxoribine in 50 mL of ethanol solution and stir well to prepare a 2 g / L loxoribine solution; prepare a mixed solvent of ethanol:water = 8:1, add γ-mercaptopropyltrimethoxysilane (PropS-SH) to it to prepare a 50 mL 5% (v / v) organosilane solution.

[0066] (5) Adjust the pH value of the above loxoribine solution to 8 with 0.5 mol of ammonia water, mix the above-prepared organosilane solution with the loxoribine solution, add 2.0 g of the above-prepared nano-filler, and then add 5 g of pyrite powder (particle size about 100 μm), stir the mixed solution at a water temperature of 25 °C for 6 h, then filter out the passivated pyrite powder, dry it at 25 °C for 24 h, and finally obtain passivated-coated pyrite, named PL+HH@PE-2.0 passivated ore.

[0067] (6) Add the above passivated ore to 120 mL of hydrochloric acid solution (pH = 1) and react for 60 d, and test the total iron and SO 4 2- concentration in the leaching solution, and it is obtained that compared with the original pyrite ore, the release reduction of the total iron and SO 4 2- concentrations of the passivated pyrite are 68.09% and 58.09% respectively.

[0068] Example 5

[0069] Stir 1 g of the nano-filler wrapped with four layers of polyelectrolyte layers prepared in Example 1 in 100 mL of pure water (pH = 6.5), hydrochloric acid solutions with pH values of 1.0, 3.0, and 5.0 for 180 min, and test the content of 8-hydroxyquinoline in the solution. The results are as Figure 3as shown

[0070] When the solution pH = 1, the release amount of 8-hydroxyquinoline is 11.88 mg / L. Compared with the halloysite nanotubes loaded with 8-hydroxyquinoline without encapsulating polyelectrolytes, the release amount of 8-hydroxyquinoline in the nanocomposite filler encapsulated with four layers of polyelectrolyte layers is reduced by 31.54%. When the solution pH is 3.0 compared with pH = 1, the release amount of 8-hydroxyquinoline in the nanocomposite filler is reduced by 18.60%. When the solution pH is 5.0 compared with pH = 1, the release amount of 8-hydroxyquinoline in the nanocomposite filler is reduced by 61.28%. When the solution is pure water compared with pH = 1, the release of 8-hydroxyquinoline in the nanocontainer is reduced by 74.75%. Compared with the halloysite nanotubes loaded with 8-hydroxyquinoline without encapsulating polyelectrolytes in pure water, the release amount of 8-hydroxyquinoline in the nanocomposite filler encapsulated with four layers of polyelectrolyte layers is reduced by 78.28%. Thus, it can be seen that the nanocomposite filler encapsulated with polyelectrolyte layers prepared by the present invention can significantly slow down the release amount of 8-hydroxyquinoline, and the slowing effect is better in the neutral to weakly alkaline environment.

[0071] Example 6 (encapsulating two layers of polyelectrolytes, pH = 1)

[0072] The difference between the nanocomposite filler of this comparative example and that of Example 1 is only that only two layers of polyelectrolyte layers are encapsulated. 1 g of the obtained nanocomposite filler is added to 100 mL of hydrochloric acid solution with a pH value of 1 and stirred for 180 min. The content of 8-hydroxyquinoline in the solution is measured. It is found that compared with the nanocontainer without encapsulating polyelectrolytes, the release amount of 8-hydroxyquinoline in the nanocontainer encapsulated with two layers of polyelectrolyte layers is reduced by 27.66%.

[0073] Example 7 (encapsulating six layers of polyelectrolytes, pH = 1)

[0074] The difference between this comparative example and Example 1 is only that six layers of polyelectrolyte layers are encapsulated. 1 g of the obtained nanocomposite filler is added to 100 mL of hydrochloric acid solution with a pH value of 1 and stirred for 180 min. The content of 8-hydroxyquinoline in the solution is measured. It is found that compared with the nanocontainer without encapsulating polyelectrolytes, the release amount of 8-hydroxyquinoline in the nanocontainer encapsulated with six layers of polyelectrolyte layers is reduced by 44.62%.

[0075] Example 8 (only encapsulating two layers of polyelectrolytes, pure water)

[0076] The difference between the nanofiller in this comparative example and Example 1 is that only two polyelectrolyte layers are wrapped. 1 g of the obtained nanofiller is added to 100 mL of pure water (pH = 6.5) and stirred for 180 min. The content of 8-hydroxyquinoline in the solution is tested. It is found that compared with the nanocontainer not wrapped with polyelectrolyte, the release amount of 8-hydroxyquinoline in the nanocontainer wrapped with two polyelectrolyte layers is reduced by 46.56%.

[0077] Example 9 (wrapped with six layers of polyelectrolyte, pure water)

[0078] The difference between this comparative example and Example 1 is that six polyelectrolyte layers are wrapped. 1 g of the obtained nanofiller is added to 100 mL of pure water (pH = 6.5) and stirred for 180 min. The content of 8-hydroxyquinoline in the test solution is tested. It is found that the release of 8-hydroxyquinoline in the nanocontainer wrapped with six polyelectrolyte layers is reduced by 87.33% compared with the nanocontainer wrapped with unwrapped polyelectrolyte.

[0079] Comparative Example 1 (adding only silane coupling agent)

[0080] (1) First, a mixed solvent of ethanol and water in a ratio of 8:1 was prepared, and γ-mercaptopropyltrimethoxysilane (PropS-SH) was added thereto to prepare 100 mL of a 5% (v / v) organosilane solution. 5 g of pyrite powder (with a particle size of about 100 μm) was added to the organosilane solution, and the mixed solution was stirred at a water temperature of 25° C. for 6 h. The pyrite powder after the passivation treatment was then filtered out and dried at room temperature of 25° C. for 24 h to finally obtain a passivation-coated pyrite, i.e., a silane-passivated ore.

[0081] (2) The above passivated ore was added to 120 mL of hydrochloric acid solution (pH = 1) and reacted for 60 days. The total iron and SO in the leaching solution were tested. 4 2- The concentration of total iron and SO in the passivated pyrite was compared with that in the original pyrite. 4 2- The release reductions of the concentrations were 12.73% and 5.61%, respectively.

[0082] Comparative Example 2 (adding only lorsulphonate solution and silane coupling agent)

[0083] (1) Dissolve 0.1 g of Lawson's ketone in 50 mL of ethanol solution and stir thoroughly to prepare a 2 g / L Lawson's ketone solution; prepare a mixed solvent of ethanol and water in a ratio of 8:1, add γ-mercaptopropyltrimethoxysilane (PropS-SH) thereto to prepare 50 mL of a 5% (v / v) organosilane solution.

[0084] (2) Adjust the pH value of the above-mentioned lasoctone solution to 8 with 0.5 mol of ammonia water. Mix the above-prepared organosilane solution with the lasoctone solution, add 5 g of pyrite powder (particle size about 100 μm), stir the mixture at a water temperature of 25 °C for 6 h, then filter out the passivated pyrite powder and dry it at 25 °C for 24 h. Finally, obtain passivated-coated pyrite, named PL passivated ore.

[0085] (3) Add the above passivated ore to 120 mL of hydrochloric acid solution (pH = 1) and react for 60 d. Test the total iron and SO 4 2- concentration in the leaching solution, and it is obtained that compared with the original pyrite ore, the release reduction of the total iron and SO 4 2- concentration of the passivated pyrite are 37.62% and 30.49% respectively.

[0086] Comparative Example 3 (untreated)

[0087] Add 5 g of untreated pyrite ore powder to 120 mL of hydrochloric acid solution (pH = 1) and react for 60 d. Test the total iron and SO 4 2- concentration in the leaching solution, which are 4234.6 mg / L and 7346.1 mg / L respectively.

[0088] Comparative Example 4 (not coated with polyelectrolyte, pH = 1)

[0089] (1) The steps of loading 8-hydroxyquinoline on halloysite nanotubes are the same as in Example 1.

[0090] (2) Add 1 g of the halloysite nanotubes loaded with 8-hydroxyquinoline obtained in step (1) to 100 mL of hydrochloric acid solution with a pH value of 1 and stir for 180 min. Test the content of 8-hydroxyquinoline in the solution, and it is obtained that the release amount of 8-hydroxyquinoline in the nano-filler without coating polyelectrolyte is 17.40 mg / L.

[0091] Comparative Example 5 (not coated with polyelectrolyte layer, pure water)

[0092] The difference between the nano-filler of this comparative example and that of Example 1 is only that the polyelectrolyte layer is not coated. Add 1 g of the obtained nano-filler to 100 mL of pure water (pH = 6.5) and stir for 180 min. Test the content of 8-hydroxyquinoline in the solution, and it is obtained that the release amount of 8-hydroxyquinoline in the nano-container without coating polyelectrolyte is 13.81 mg / L.

Claims

1. A self-healing composite passivator, characterized in that: it includes a nano filler, lauroxone and a silane coupling agent; the nano filler is composed of a nano passivator coated with a polyelectrolyte layer; the nano passivator is composed of a guest passivator loaded in halloysite nanotubes; in the self-healing composite passivator, the mass ratio of the nano filler, lauroxone and the silane coupling agent is 0.1~2: 0.01~0.2: 3~5; the polyelectrolyte layer includes a cationic polyelectrolyte layer and an anionic polyelectrolyte layer; the component of the cationic polyelectrolyte layer is poly(diallyldimethylammonium chloride); the component of the anionic polyelectrolyte layer is sodium polystyrene sulfonate; the polyelectrolyte layer is alternately composed of 1~3 layers of cationic polyelectrolyte layers and 1~3 layers of anionic electrolyte layers.

2. A self-healing composite passivator according to claim 1, characterized in that: the loading amount of the guest passivator in the nano passivator is 0.1~5wt%.

3. A self-healing composite passivator according to claim 1, characterized in that: the self-healing composite passivator contains a solvent; the solvent contains water and an alcohol solvent; in the self-healing composite passivator, the total mass content of the nano filler, lauroxone and the silane coupling agent is 1~10%.

4. A passivation treatment method for inhibiting pyrite oxidation, characterized in that: pyrite is placed in the self-healing composite passivator according to any one of claims 1~3 and stirred for reaction.

5. A passivation treatment method for inhibiting pyrite oxidation according to claim 4, characterized in that: the stirring reaction conditions are: temperature is 25~35°C, time is 4~6h, and pH is 1~7.

6. A passivation treatment method for inhibiting pyrite oxidation according to claim 5, characterized in that: the mass-volume ratio of the pyrite to the self-healing composite passivator is 1g:10~20mL.

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